In Diesel pile hammers, such as the conventional one shown in FIG. 1, the piston (1) during its free descent in the cylinder (2), pushes a cam lever (3) facing on the inside of said cylinder (2) at the fuel pump attached to the cylinder whereby the cam lever pushes down a plunger (4) at its end to close the fueling port (7) in the pump chamber (5) connected to the fuel tank (6) thereby to produce compressed state within the pump chamber (5). When the pressure in the pump chamber (5) has risen above the opening pressure for the delivery valve (8), the fuel in the pump chamber (5) pushes the delivery valve open and is sprayed through a nozzle (9) onto the part-spherical saucer (11) formed on the top of the impact block (10) which is riding on the pile head. Because the opening pressure for said delivery valve (8) is very low and the delivery valve (8) provides a restriction, the fuel sprayed from the nozzle (9) is not at all atomized but remain as liquid on the saucer (11).
As the piston (1) further goes down, it closes the suction and exhaust port (12), thus producing a compressed state of high temperature and pressure within the cylinder. When the lower end of the piston (1) strikes the saucer (11) of the impact block (10), the fuel which has been deposited on the saucer (11) gets atomized and scattered by the impact. The particles of fuel scattered in the combustion chamber formed by the piston (1), saucer (11) and cylinder (2) will ignite and burn spontaneously under the ambient high temperature and pressure. This results in further increase in temperature and pressure in the combustion chamber, so the piston (1) is raised upward under the high gaseous pressure in the cylinder (2), discharging the combustion gas through the suction and exhaust port (12). With further ascent of the piston (1) in the cylinder (2), fresh air is induced through said suction and exhaust port (12) into the cylinder (2). The cycle is completed when the piston (1) rises up to the original point in the cylinder (2).
In this conventional Diesel pile hammer, however, the fuel spouting from the nozzle (9) and striking the saucer (11), does not all rest on the saucer but about half of the total amount of the fuel spouted may spill away-from the saucer, with the result that the spilled fuel will not receive any impact to atomize it but will remain deposited on the inner wall of the cylinder (2) without burning.
Consequently, the fuel that contributes to effective combustion is only half of the spouted quantity and even this fuel is maldistributed in the saucer so that it is distributed uniformly throughout the combustion chamber by impact. The result is that the fuel deposited on the inner wall of the cylinder (2) will flow out as unreacted fuel vapor through the suction and exhaust port thus becoming the cause for white smoke, while the fuel unevenly distributed upon the impact in combustion chamber will undergo an imperfect combustion due to local air shortage thus becoming the cause for black smoke.
It is thus seen that the conventional Diesel pile hammer has the disadvantage of causing much smoke, resulting from imperfect combustion because of inadequacy in feeding fuel to the saucer formed on the top of the impact block.